EP0145624A2 - Method and apparatus for automatically stacking flat articles - Google Patents

Abstract

The flat articles, in particular light-alloy discs, to be stacked have the same planar dimensions. The method consists, after aligning the articles in the transport direction of a conveyor, in placing them at the outlet of the latter onto two diverging outer supports, which are substantially horizontal, and whose transverse spacing, initially less than the diameter or than the smallest diagonal of the articles in question, attains at least the diameter or the largest diagonal of the said articles. It is preferable to stop the articles in their free fall by one (or more) front stop(s) and if appropriate a rear stop. The corresponding device permits, for example, the stacking of light-alloy discs without mutual excess relative friction at a rate ranging up to 5 articles per second. <IMAGE>

Description

The present invention relates to a method and a device for the automatic stacking of flat objects of the same dimensions in plan, in particular of light alloy discs.

In a large number of industrial sectors, flat products are obtained on high-speed installations and are evacuated by conveyor, generally by one (or more) conveyor belt (s) to one (or more) station (s) ) stacking, for packaging, transport or further processing.

In the prior art, a stacking device consists in placing at the end of the conveyor a receptacle of semi-rectangular section, arranged transversely with respect to the conveyor and inclined on the horizontal. Objects stack by simple gravity in this receptacle. However, this results in two drawbacks, namely on the one hand that the stacking is not perfect, the objects overflowing more or less with respect to each other, and on the other hand, that these risk being surface deterioration due to their relative sliding during stacking.

The present invention overcomes these two drawbacks.

The method consists after having substantially aligned the objects in the axis of travel of the conveyor by a means known from the prior art, to engage them at the output thereof on two substantially horizontal diverging external supports, including the transverse spacing, initially less than the diameter or the smallest diagonal of the objects considered reaches at least the diameter or the largest diagonal thereof; therefore, beyond this last position (P) the object falls substantially flat along a parabolic curve, thanks to the speed acquired, on the stack of objects being formed. If the height between position (P) and the top of the stack is large enough with respect to the horizontal speed of movement of the object, it arrives substantially vertically on the previous one, which avoids mutual sliding and by following the deterioration of the surfaces in contact.

However, in the vicinity of position (P) the object is subjected to a slight moment of tilting, around a substantially horizontal axis (Q) when the projection of the object's center of gravity (G) leaves the polygon of residual lift.

To avoid this harmful effect, it is preferable to stop the object in its free fall by one (or more) stop (s) before, before it reaches the top of the stack during formation. The height of free fall (h) between (P) and the stop is less than 20 mm and preferably between 10 and 20 mm; in this case, the object falls strictly vertically on the previous one. The lower the free fall height, the greater the regularity and precision _? stacking. The free fall height is adjusted by controlling the exit speed of the conveyor depending on the nature and dimensions of the objects to be stacked.

Stacking is even more perfect if, in addition, an axial rear stop is used, delimiting the stacking space with a slight play, which can go up to a few millimeters.

Of course, the stack of objects in formation can be stationary or mobile along a vertical axis. In the first case, the total height of fall is variable; in the second case, the total height of fall can be made substantially constant by progressive and programmed lowering of the base carrying the stack of objects during its formation, using known means: position detector, mechanical devices , cylinders, etc ...

The device therefore essentially comprises at the level of the conveyor belt two diverging substantially horizontal external supports in the form of slides, rails, etc., made of suitable materials, preferably oriented towards the direction of movement of the aligned objects.

To avoid surface deterioration and minimize energy consumption, the supports are preferably provided with non-metallic cylindrical rollers, substantially contiguous. It has been noted that the diameter of rollers 0g must be smaller the smaller the diameter or the diagonals of the object (0o). Other means such as Motorized conveyor belts can also be used.

The angles (OÇ) of each of the supports with the scrolling axis are small, generally between 1 ° and 15 ° and they are preferably equal and between 5 and 10 °. The stacking precision is all the better when the angles (q) are smaller.

The supports are adjustable in symmetrical position, relative to the axis of travel, using a device consisting of two transverse axes constituting slides and a central transverse screw, controlled at its ends, by a square end piece , which has an inverted pitch thread which engages in corresponding nuts fixed to the support.

A similar system makes it possible to determine the position of two longitudinal rulers whose spacing is equal to the diameter of the objects to be stacked; these are intended to perfect the centering of the objects to be stacked at the entrance to the stacking device. As a result, the rules extend from the end of the conveyor to the supports and have a converging entry.

The device also includes one (or more) front stop (s) which delimit the location of objects during their free fall. They can consist either of a flat stopper perpendicular to the direction of travel of the objects, or of two vertical cylindrical rods symmetrical with respect to the axis of travel of the products. To avoid deterioration of the edges of the objects due to impacts on the (or) stop (s), these are preferably made (or coated) of a damping material such as rubber or a plastic material.

The device making it possible to simultaneously adjust the position of the two front stops, symmetrically with respect to the scrolling axis, consists of two arms placed symmetrically with respect to the scrolling axis, each of them carrying at one of its ends a vertical stop before circular section. The arm of rectangular or square section is provided with a rack on its vertical lateral face; these arms slide longitudinally in the corresponding slides and are moved by two identical pinions, mounted on the same vertical axis and which mesh with the racks. These two pinions are controlled by an axis carrying a: operating crank and a positioning pinion, stopped by a blocking system.

The rear stopper is arranged vertically on the travel axis and is fixed to the frame as close as possible to the end of the conveyor belt. Its upper end is at the level thereof and preferably has a plane inclined downstream, with an angle (p) up to 15 °.

If, for reasons of space, it cannot be placed immediately adjacent to the end of the conveyor belt, two parallel raceways are placed on each side of the latter, provided with rollers, in the space between the conveyor belt and the stop, at the supports.

• La figure 1 représente en élévation coupe suivant le tracé AA de la figure 2 de l'ensemble du dispositif d'empilage.
• La figure 2 représente une vue en plan de l'ensemble du dispositif.
• La figure 3 représente une vue en plan et de côté d'un support à galets.
• La figure 4 précise la trajectoire des objets pendant leur chute libre sans butée (fig. 4A) ou avec butée avant (fig. 4B).
• La figure 5 représente les positions de chute (P) et de basculement (Q) pour des objets de forme géométrique différente.
• La figure 6 donne une vue en long du dispositif d'empilage proprement dit.
• La figure 7 donne le détail de la disposition de la butée arrière.
• Les figures 8 et 9 représentent le dispositif de réglage et de blocage des butées avant.

The invention will be better understood using the following figures and examples:

• Figure 1 shows in sectional elevation along the line AA in Figure 2 of the entire stacking device.
• Figure 2 shows a plan view of the entire device.
• Figure 3 shows a plan and side view of a roller support.
• Figure 4 specifies the trajectory of the objects during their free fall without stop (fig. 4A) or with front stop (fig. 4B).
• FIG. 5 represents the positions of fall (P) and of tilting (Q) for objects of different geometric shape.
• Figure 6 gives a long view of the stacking device itself.
• Figure 7 gives the detail of the arrangement of the rear stop.
• Figures 8 and 9 show the device for adjusting and blocking the front stops.

Figures 1 and 2 show a frame (1) supporting the conveyor belt (2) which runs along the axis (3) in the direction of the arrow (F). It transports flat objects to be stacked (4), here circular, pre- roughly centered using a known device (not shown). At the level and at the front of the conveyor belt, two divergent supports (5) with rollers (6) are placed horizontally, the front end of which makes an angle (r ₄ ) of 15 ° with the travel axis (3) .

The rollers (6) are mounted idly on their axis and in a quasi-contiguous manner on the supports (5).

The supports (5) are linked to the frame (1) by means of two transverse guides (7) and of a shaft (8) threaded at the two ends at the same pitch but in the opposite direction, this shaft meshing with corresponding nuts , integral with the support (5) so that their spacing at the inlet is less than the diameter (or the diagonal) of the objects to be stacked (4), the length of the supports (5) being sufficient for the spacing of those -this at their downstream end is greater than or equal to the diameter (or diagonal) of the objects to be stacked. A similar device - guides (9) and threaded shaft (10) - makes it possible to move symmetrically with respect to the scrolling axis (3) two rules (12) with converging entry, for the precise centering of the objects to be stacked entering the stacking device. These rules are lined internally with an anti-friction coating.

When the object (4) arrives at position (P) (figure 5) where the spacing of the supports (5) is equal to its diameter (or its diagonal) it falls along the parabola (12) (fig. 4) on the stack (13) being formed, on a base (14) or in a container (not shown).

However, between position Q where the center of gravity of the object leaves the residual support polygon (ABCD) and position (P), the object is subjected to a tilting moment whose lever arm is equal to the distance from the center of gravity G 'to the right P.

To avoid thereby irregular stacking, the free fall height (h) is therefore limited by one (or more) stop (s) before (15) to a value preferably between 10 and 20 mm.

These front stops (15 - fig. 1, fig. 6) consist of metal cylinders, coated with "Standard". They are fixed vertically at the end arm section (16) with square section which slides in slides (17) fixed to the frame (1) in the running axis (3) and arranged symmetrically with respect thereto. The two arms (15) are provided on their vertical lateral face with racks which mesh with two identical toothed pinions (18) mounted on the same axis (19) maneuverable by the crank (20) and comprising the positioning toothed wheel (21) , stopped by the locking device (22). The axle-crank-pinion assembly is mounted on angles (23 - fig. 8) integral with the slides (17).

The rear stop (24 - fig. 7), of circular cylindrical shape, is made of "Ertalon", and fixed vertically to the frame (1) on the running axis (3). The upper end of this stop is in the plane of the conveyor belt (2) and has a plane inclined downstream making with the horizontal an angle (β) of 10 °. As in the case represented in this FIG. 7, there are placed on each side of the stop (24), between the end of the conveyor belt (2) and this stop (24), two raceways (25), comprising rollers identical to (6).

The stack of object in formation (13) on its base (14) rests on a platform (26 - fig. 1) movable in translation along two horizontal orthogonal axes and a vertical axis. The lowering of this platform is controlled by known means depending on the position of the top of the stack being formed (13).

The device according to the invention has great simplicity and does not comprise any movable member other than the rollers (6), which allows stacking at fairly high frequencies of up to five objects / second, with great security of market.

EXAMPLES

Hardened Al alloy discs, type 1050, 0 610 mm and 1.20 mm thick, were stacked at the rate of 40 discs per minute.

Al alloy discs, type 1200, in the strained condition of 0 710 mm and 4 mm thick were stacked at the rate of 80 discs per minute.

Disks of Al alloy, type 1200, in the annealed state of 0 115 mm and 4 mm thick, were stacked at the rate of 120 disks per minute.

Claims (14)

1. Method for stacking flat objects of the same dimensions in plan, previously aligned, on a conveyor (2), characterized in that they are engaged at the end of the conveyor on two diverging supports (5) symmetrical with respect to the 'axis of travel (3) and whose spacing initially less than the diameter or the smallest diagonal of the objects considered, reaches at the opposite end at least the diameter or the largest diagonal of the flat objects (4) transported. 2. Method according to claim 1, characterized in that the objects are stopped in their free fall by one (or more) stop (s) before (15). 3. Method according to claim 2, characterized in that the free fall height (h) is less than 20 mm, preferably between 10 and 20 mm. 4. Method according to one of claims 2 or 3, characterized in that the stacking (13) of flat objects (4) is limited by a rear axial stop (24) with the necessary clearance. 5. Device for stacking flat objects (4) comprising at least one conveyor (2), divergent supports (5) and a base (14) or a receptacle for forming the stack (13), characterized in that the supports make angles (x) between 1 and 15 ° relative to the direction of travel (3) of the objects (4). 6. Device according to claim 5, characterized in that the supports (5) are provided with rollers (6) almost contiguous, mounted idly on their axis. 7. Device according to one of claims 5 or 6, characterized in that the supports (5) are adjustable in position symmetrically with respect to the axis of travel (3). 8. Device according to one of claims 5 to 7, characterized in that the objects are precisely centered on the scroll axis (3) by rulers (11), adjustable in position symmetrically with respect to this scroll axis (3). 9. Device according to claims 5 to 8, characterized in that the front stops (15) are adjustable in position symmetrically relative to the axis of travel (3). 10. Device according to claim 9, characterized in that the front stops (15) are mounted at the end of arms (16) movable in translation in slides (17), arranged symmetrically relative to the axis of travel ( 3) and moved by two identical pinions (18) mounted on a shaft (19) which mesh on the corresponding racks, integral with the arms (16). 11. Device according to one of claims 9 or 10, characterized in that the position of the front stops (15) is fixed by a toothed wheel (21) integral with the axis (19) and stopped by a locking device ( 22) adequate. 12. Device according to one of claims 5 to 11, characterized in that it comprises an axial rear stop (24). 13. Device according to claim 12, characterized in that between the conveyor (2) and the axial stop (24) is disposed, on each side of the latter, a raceway (25). 14. Device according to one of claims 9 to 13, characterized in that the stops (15, 24) consist (or coated) of an anti-shock product.

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